In its press release PBS explains how the co-anchoring duties will work out:

"Ifill and Woodruff will anchor the broadcast together Monday through Thursday each week. On Fridays, Woodruff will anchor solo as Ifill hosts Washington Week that evening. This will mark the first time a network broadcast has had a female co-anchor team."

"Tuesday's announcement was, among other things, an admission that a rotating anchor format is not preferable for a long period of time. At the end of 2009, as Mr. Lehrer neared retirement, Ms. Ifill and Ms. Woodruff and three other correspondents — Jeffrey Brown, Ray Suarez and Margaret Warner — started to take turns anchoring the 'NewsHour' with him. After he retired, this format remained in place, with two of the five anchoring each weeknight. 'It was a way to give each of them a chance,' said Linda Winslow, the program's executive producer, praising the team of 'really powerful people.'

"But the arrangement made production of the 'NewsHour' unwieldy at times, and it confused viewers, at least some of whom expect to see the same face or faces every night."